Method of molding double-walled hollow concrete blocks



Dec. 23, 1952 J. M. WILSON 2,622,303

METHOD OF? MOLDING DOUBLE-WALLED HOLLOW CONCRETE BLOCKS Filed Dec. 28,1949 6 I It 21 ,Z QQZ ZMEZZHH Z 19 a 14' 11 i 14' FIG :1.

Arr Jr Patented Dec. 23, 1952 FFECE 2,622,303 METHOD OF" MOLDINGDOUBLE-WALLIS!) HOLLOW CONCRETE BLOCKS John M. Wilson, Glasgow, ScotlandApplication December 28, 1949, Serial No.'1-35,37-9' In" Great-BritainFebruary 4, 1948 6 Claims. 1

This invention relates to the moulding of double-walled hollow concreteblocks such as commonly used inthe building trade.

The present invention comprises a method of moulding a double-walledhollow concrete block in which steam is introducedfor a predeterminedtime directly into the mould into contact with the: uncured block inorder to speed up the curing of said block.

The invention is especially applicable to hol low concrete blockscomprising two spaced walls tied together by interconnecting ties.Preferably, such blocks are moulded with the spaced walls arrangedhorizontallyabove one another.

Preferably, a mould is adapted to make a number of blocks; arranged endto end, a dividing Wall between the blocks having. an opening to thehollow interior of the blocks so as to allow for the passage of thesteam throughout the mould.

Preferably, a number of moulds are arranged side by side in a bank. aside member of one mould being common to the adjacent mould and havingopenings to the hollow interior of the blocks so as to allow for thepassage of the steam throughout the bank of moulds.

The" steam may advantageously be introduced to the mould simultaneouslythrough? a nozzle at each end, said nozzles beingarranged directlyopposite one another so that the' two' steam jets meet; therebyassisting in spreading the steam throughout the-bank of moulds.

An embodiment of the invention will now he described, by way of example,with reference to the accompanyingdrawings whereon:

Fig. 1 is a s'ection'through a--mould on the line |"-l of Fig. Zand Fig.2 is a-plan view of a bank ofmoulds; 7

Referring to the drawings, a bank of moulds comprises a series ofindividual moulds Ill arrangedside by side so that a sidemember of eachmould: is common to the adjacent mould. I The mouldsin thepresentexample are suitable for moulding hollow concreteblockshaving twospaced-walls H' and l-l'a tied together" by inter-- connecting ties lib.These blocks are moulded with-their spaced walls arranged horizontally,one above the other (asshown iii-Fig. 1 by chain dottedl'ines-f'o'rclarity). In the p'res'ent example each mould adapted toaccommodate four blocks;- butthis number may be varied as desired;

Each mouldcomprises side andLend members. The-end members I'Z' fitbetween theside'members I3} being positioned by suitable" stops (notshown) The end members act as spacing pieces for keeping the sides ofthe mould at the exact distance apart. A bank of say forty-four mouldsis thus assembled. The side members 13a at the extreme ends of the bankand certain intermediate side members (in the example, every eleventhsidemember) are provided with a dowel pin (not shown) at each end whichfit into 00-- operating recesses in the base beams It on which themoulds rest. Said cooperating pins and apertures servepositively toposition the side members and also-the bank of moulds, as a whole, on

said base beams.

The procedure in moulding. the blocks is briefly as follows: i,

Each mould is fitted with three equi-spaced transverse division platesit, which extend upwards from the bottom of the mould an amount givingthe desired thickness of the lower spaced wall Ila of the block, theseplates thus acting as dividing walls between the four blocks. Theconcrete is then poured into the mould and levelled off flush with saidplates. An upper mould plate. comprising two half plates [6 havingmating alternate projections and recesses of zig-zag. shape as shown inFig. 2-,. is then fitted inposition in the mould. Said projections havecut-away portions ll at their apices to allow for the interconnectingties lib tobe placed in position. The upper mould plate is arrangedparallel to the top and bottom of the mould and at a distance from thetop equal to the desired thickness of the upper spacedwall H. Theinterconnecting ties 1 lb are inserted through the cut-away portions H,their lower ends being ernbeddedv in the concrete of the lower wall Maand the upper ends extending above the upper plate IS. The uppertransverse division plates it are then fitted in position and theconcrete is poured into the spaces formed above said upper mouldingplates and levelled off' flushwith the top of themould. u

When all the moulds in the bank are filled, steam is introduced into themould. The end members of moulds spaced at regular intervals inthe bankare provided with a connection IE! to which the steam supply isconnected. The construction of the mould is such that the steam can passthroughout the entire length of the mould (as will be seen from Fig. l)and also seeps through the zig-zag plates rem t-he'u-pper wall [-1-oftheblock; fl heside members l3'lia've openings 24} to the hollowportions ofthe blocks and thus the steam is free to pass thrciughout thebank of moulds. In the resent example;

the bank of moulds has six steam connections on each side spaced atregular intervals and being connected to the steam supply by a flexibleconnection 2|. It is advantageous to introduce the steam into the mouldsimultaneously at each end and to have the connections directly oppositeone another so that the jets of steam meet and thereby the spreading ofthe steam through the bank of moulds is facilitated. The steam supplymay be connected to each set of connections in turn or to any desirednumber simultaneously. For this purpose the connections 19 mayincorporate a one way valve (not shown) or the free connections may beotherwise sealed off.

By introducing steam into the moulds, the curing of the concrete blocksis considerably accelerated. As a result of this it is possible tomanufacture more blocks in a given number of moulds in a given time.Thus the cost of the steam which is relatively small is more thancompensated by the time of curing, so that the same moulds can be usedtwo or maybe three times more than if no steam was used, and hence asmaller factory and a smaller outlay on moulds and other equipment isrequired.

The steam is supplied from the boiler at about 60-100 lbs. per squareinch but passes through a reducing valve. In practice it has been foundthat blocks should, on an average, be heated to 70 or 80 degreesCentigrade. This heat is maintained for about 20 minutes and as a resultthere is a considerable reduction in time of curing.

The duration of heating of course varies appreciably in respect of therequired time of ouring and it also depends on the surroundingtemperature in the atmosphere, the lower the surrounding temperature thelonger the heating required.

As a result of this invention the time required to leave the concreteblock to set in the mould is greatly reduced, for example, concretewhich would normally take twenty-four hours to set will set in six hourswith half an hours steaming. These times will depend on various factors(for example type of mixture, climatic conditions, temperature ofsteam), but the ratio will always be substantially in the sameproportions.

This particular invention is especially applicable to the double-walledblocks as the heating is applied to the interior surface and theconduction of the heat is from the inside out, thus ensuring effectiveaction on the whole block. It has been proposed before to put blocks insteam chambers yet While this would economise in steam, it involves alot of handling and the heat would be applied from the exterior of theblock inwards and without, effective heat circulation there may beunequal temperature and curing.

In practice it is found beneficial to spray the upper spaced wall of theblock to keep it moist, as it will be appreciated that the condensatewill fall on the lower spaced wall and the upper spaced wall would beinclined to dry out.

I claim:

1. A method of moulding double-walled hollow c-oncrete'blocks with tiesbetween the opposite walls thereof comprising pouring green concreteinto the bottom of a mould to form one wall of the blocks, inserting inan upper part of the mould at least one pair of co-operating mould.plates having opposed mating projections and recesses alternating andcut-out parts on their mating edges adapted to define locations forties, inserting ties in said locations, pouring green concrete into theupper part of the mould on said mating plates to form the other wall ofthe blocks spaced above the first wall and bound thereto by the ties,introducing steam into the mould in the region between the two wallswhereby it first makes contact with the inner surfaces of said walls andspeeds up the hardening of the concrete, and then supplying moisture tothe upper surfaces of the upper walls of the blocks to keep them moistduring the steam treatment.

2. A method of moulding double-walled hollow concrete blocks with tiesbetween the opposite walls thereof comprising pouring green concreteinto the bottom of a mould to form one wall of the blocks, inserting inan upper part of the mould at least one pair of co-operating mouldplates having opposed mating projections and recesses alternating andcut-out parts on their mating edges adapted to define locations forties, inserting ties in said locations, pouring green concrete into theupper part of the mould on said mating plates to form the other wall ofthe blocks spaced above the first wall and bound thereto by the ties,introducing steam in jets into the mould in the region between the twowalls from opposed sides of the mould whereby the steam jets meet andthe steam spreads throughout the region between the inner surfaces ofthe two walls and first makes contact with the inner surfaces of theWall to speed up the hardening of the concrete, and then supplyingmoisture to the upper surfaces of the upper walls of the blocks to keepthem moist during the steam treatment.

3. A method of moulding double-walled hollow concrete blocks with tiesbetween the opposite walls thereof comprising pouring green concreteinto the bottom of a mould to form one wall of the blocks, inserting inan upper part of the mould at least one pair of co-operating mouldplates having opposed mating projections and recesses of zig-zagformation alternating and cutout parts at the apices of the projectionsadapted to define locations for ties, inserting ties in said locations,pouring green concrete into the upper part of the mould on said matingplates to form the other Wall of the blocks spaced above the first walland bound thereto by the ties, and introducing steam into the mould inthe region between the two walls whereby it first makes contact withthe, inner surfaces of said walls and speeds up the hardening of theconcrete, and then supplying moisture to the upper surfaces of the upperwalls of the blocks to keep them moist during the steam treatment.

4. A method of moulding double-walled hollow concrete blocks with tiesbetween the opposite walls thereof comprising pouring green concreteinto the bottom of a mould to form one wall of the blocks, inserting inan upper part of the mould at least one pair of co-operating mouldplates having opposed mating projections and recesses ofzig-zagformation alternating and cut-out parts at the apices of theprojections adapted to define locations for ties, inserting ties in saidlocations, pouring green concrete into the upper part of the mould onsaid mating plates to form the other wall of the blocks spaced above thefirst wall and bound thereto by the ties, introducing steam in jets intothe mould in the region between the two walls from opposed sides of themould whereby the steam jets meet and the steam spreads throughout theregion between the inner surfaces of the two walls and'first makescontact with the inner surfaces ofthe walls to speed up hardening of theconcrete, and then spraying moisture on to the upper surfaces of theupper walls of the blocks to keep them moist during the steam treatment.

5. A method of moulding double-walled hollow concrete blocks with tiesbetween the opposite walls thereof in a multiple mould wherein theblocks are moulded with the spaced walls arranged horizontally above oneanother and wherein adjacent faces of adjacent blocks are separated bydividing members common to adjacent moulds, comprising providingopenings in the dividing members in the parts thereof between theinter-wall spaces to provide intercommunication between said spacesthroughout the entire multiple mould and providing nozzles at spacedlocations along the sides of the multiple mould in the region of theinter-wall spaces, and, after the concrete has been poured to form theblocks, introducing steam into the 'mould 20 REFERENCES CITED Thefollowing references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 261,364 Loring July 18, 1882652,732 Ransome June 26, 1900 732,674 Bell et a1 June 30, 1903 782,230Finger Feb. 14, 1905 961,659 Taylor June 14, 1910 1,285,056 Cutler Nov.19, 1918 1,480,740 Barkschat Jan. 15, 1924 1,570,998 Egger Jan. 26, 1926

